Seed beetle, also known as been weevil (Acanthoscelides obtectus), is small in size, but a great world traveler. Like so many other species, this beetle is coping very well in conditions that people are shaping to their needs. Thus, it is very common that you find seed beetles in your pantry or shelf, in a jar filled with beans. This been weevil should not be mistaken with a common wooden weevil (e.g. Anobium punctatum) that attacks timber, floors and old furniture.

Seed beetle – a small passenger of high mileage.

In not so distant past, around 12 000 years ago, seed beetle roamed the Central America meadows in the search of wild bean seeds. However, when the ancient peoples of America managed to domesticate beans and to keep (harvest) their seeds, the life of seed beetles become more dynamic. Following trade routes, seed beetle successfully “conquered” numerous storages in cities throughout Central and South America. In 16th century small number of this insect found their way in the pantry of a Spanish ship. When they reached Europe, it was easy to spread across the continent, and later, the whole world.

Life cycle of the seed beetle consists of three phases. After mating, females lay around 80 eggs from which mobile larvae are hatched. These mobile larvae burrow the bean seed where development and metamorphosis are completed. Time required for a complete development of an adult from a single egg is around one month.

The seed beetle is around 4mm in length with greyish-brownish tones. Unique differences between males and females can be noticed after careful observation of the rear end of the body. For example, this spot in females’ body has a series of white stripes that form characteristic mark, while males do not possess those distinct stripes. Intent observer might also notice that the shape of the body is rounder in females, compared to males. These two characteristics are the most conspicuous and that is the simplest way to differentiate sexes in seed beetles.

This insect frequently causes great damage to bean seeds in storages and fields. Beside beans, this seed beetle can consume other leguminous plans (chickpea, mung bean etc.). According to some estimates, damage caused by this insect can reach as high as 50% of total yields.

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